Pneumatic counting device



Jan. 23, 1968 s. M. I OVELESS PNEUMATIC COUNTING DEVICE 2 Sheets-Snee l Filed Aug.

Jan. 23, 1968 s. M. Low-:LESS

PNEUMATIC COUNTING DEVICE 2 Sheets-Sheet 2 Filed Aug. 5, 1965 United States Patent O 3,364,945 PNEUMATICI COUNTING DEVICE Stanley M. Loveless, Oshtemo Township, Kalamazoo County, Mich., assignor to General Gas Light Company, Kalamazoo, Mich., a corporation of Michigan Filed Aug. 5, 1965, Ser. No. 477,521 16 Claims. (Cl. IS7-624.11)

This invention relates to a pressure fluid valve and more particularly relates to a programming valve capable of shifting after application of 'a predetermined number of fluid signals thereto.

A wide variety of fluid controlled or energized machines are known which respond to the occurrence of a predetermined pneumatic or hydraulic pressure. Further, machines of such type are known in which the uid pressure is alternately raised and lowered at some point in the fluid supply to provide a sequence of pressure pulses for operating a part of the machine in a sequence of steps synchronized with the pressure pulses. Actuation of a further part by the last pressure pulse in the sequence may often be required. As an example, it may be desired to operate a first pressure fluid cylinder several times and then operate a second cylinder, thereafter repeating the cycle.

The aforementioned lfurther part can be actuated upon occurrence of a pressure pulse by providing a suitable device for counting the pressure pulses of the sequence. Then, given the number of pulses in the sequence, the aforementioned further part can be actuated upon occurrence of the last-numbered pulse.

In the past, energization of the further part at the end of such a sequence of pulses has generally required a collection of several different units of relatively complex construction. More particularly, such collection has generally included a counting unit for counting the pressure pulses. Such collection has further included a valve and a source of iiuid under pressure, the valve being connected between the further part and the source of liuid under pressure and being actuable by the counting unit at the end of the counting cycle for connecting the pressure fluid source to the further part.

Such a collection of devices is generally disadvantageous, particularly when the individual devices are such relatively complicated in construction both from the standpoint of manufacturing expense and from the standpoint of maintenance costs. Moreover, such a collection of units is generally space consuming, awkward to assemble and install on the machine and generally relatively heavy.

Hence, the objects of this invention include:

(l) To provide a programming valve capable of actuation after the application of a predetermined number of fluid pressure pulses thereto.

(2) To provide a programming valve, as aforesaid, which is capable of opening upon occurrence of the last of said preselected number of pressure pulses thereto for passing the last of such pulses therethrough to a load.

(3) To provide a programming v-alve, as aforesaid, particularly adapted for operation by gas under pressure, such as compressed air, and operable by fluid pulses varying over a relatively wide pressure range.

(4) To provide a programming valve, as aforesaid, which combines the functions of a counting device and a valve energizable by such a counting device and which may energize a load directly with one of the counted pulses, thereby eliminating the need for a pressure uid supply additional to the pulses or alternatively, may be arranged to energize the load through an external relay valve fed by an additional source.

(5) To provide a programming valve, as aforesaid, which at least in certain embodiments is readily adjustable for varying the number of pulses, below a preselected ICC maximum number, counted prior to opening without modifying or dismantling the counting valve.

(6) To provide a programming valve, as aforesaid, which is quickly and readily adaptable under field conditions for changing the preselected maximum number of pulses which can be counted.

(7) To provide a programming valve, as aforesaid, which is capable of automatically resetting itself at the end of a counting cycle in response to the end of a preselected pressure pulse in the cycle.

(8) To provide a programming valve, as aforesaid, which is capable of passing the entire pressure pulse envelope to the load including both the initial pressure increase and the succeeding pressure drop and which is capable of operation by pressure pulses of widely varying duration, spacing and shape, requiring only a relatively small fluid quantity input to achieve a counting step.

(9) To provide a programming valve, as aforesaid, which is useable in a wide variety of applications with a wide variety of loads, pressure liuid sources and types of pressure fluid without modification, which may be used for monitoring, energization and control of pressure responsive devices and fluid distribution systems of various types and which comprises a single unit capable of manufacture in a compact and relatively light-weight form.

(10) To provide a programming valve, as aforesaid, capable of manufacture in a wide variety of sizes and flow capabilities, which is relatively simple in construction, which requires a minimum of parts and which is readily manufacturable in large or small quantities of a wide variety of materials.

(11) To provide a programming valve, as aforesaid, which is rugged in construction, which is capable of long use under disadvantageous conditions with little or no maintenance and which can be readily maintained by service presonnel acquainted with apparatus of this general type without special training.

Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.

In the drawings:

FIGURE 1 is an inlet end view of a programming valve embodying the invention.

FIGURE 2 is a central sectional view substantially taken on the line Il-II of FIGURE 1 and showing the programming valve connected between a source of pressure fluid and a load.

FIGURE 3 is' a sectional view taken on the line III-III of FIGURE 2.

FIGURE 4 is a central cross-sectional view of the valve of FIGURE 2 with the parts thereof in a different position and with an additional abutment member added t0 increase maximum number of pulses to be counted.

FIGURE 5 is a partially broken fragment of FIG- URE 2 disclosing a modification.

FIGURE 6 is a fragment of FIGURE 2 disclosing a further modification.

FIGURE 7 is an enlarged fragmentary sectional view taken on the line VII- VII of FIGURE 4.

-FIGURE 8 Iis an oblique View of a modified valve embodying the invention.

FIGURE 9 is substantially a central cross-sectional View of the valve of FIGURE 8 generally as taken on the line IXAX of FIGURE 1o.

FIGURE l0 is a sectional view substantially taken on the line X-X of FIGURE 9.

FIGURE l1 is an enlarged fragment of FIGUR-E 9.

FIGURE 12 is a block diagram disclosing an alternative connection of programming valves embodying the invention.

Certain terminology will be used in the following description for convenience in reference only and'will not be limiting. The words upwardly, downwardly, rightwardly and leftwardly will designate directions in the drawings to which reference is made. The word forwardly will refer to the normal direction of uid ow through the valve such being from left to right in FIGURE 2 and, hence, from the source to the load. The word rearwardly will designate the opposite direction. The words inwardly and foutwardly will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Said terminology will include the words above specically mentioned, derivatives thereof and words of similar import.

GENERAL DESCRIPTION The objects and purposes of this invention are met by providing a programming valve having a housing deiining a chamber therewith. A piston is reciprocable in the chamber in response to a fluid pressure drop thereacross in the direction of decreasing pressure. Counting means Yresponsive to successive pressurizations of the chamber on one side of the piston are provided for allowing movement of the piston through successive steps of limited length. Valve means responsive to the position of therpiston in the chamber after a preselected number of steps are providedfor permitting uid ow past the piston when the piston is adjacent the ends of its travel and for otherwise preventing such flow.

DETAILED DESCRIPTION The programming valve (FIGURES l and 2) embodying the invention includes a housing 11. The housing 411 has an elongated, preferably coaxial, chamber 12 therewith which isV preferably of circular cross section. The housing 11 comprises `an opposed, generally cupshaped pair of end members 13 and 14 joined by an extension structure generally indicated at 16 and hereinafter described. The end members 13 and 14 have coaxial-` ly opposed, preferably circular recesses 17 and 18, respectively.

The recess 18 in the rightward end member 14 is preferably larger in diameter than the recess 17 for purposes appearing hereinafter. lIn the particular embodiment shown, a trip rod 21 is coaxially threaded into the bottom, i'.e., the leftward end, of the recess 17 as indicated at 22 and extends rightwardly therefrom to a point intermediate the ends of the recess 17. An inlet opening 23 communicates with the bottom of recess 17 adjacent the trip rod 21 and extends axially leftwardly therefrom. -In the particular embodiment shown, the inlet opening 23 communicates at its leftward end with a further opening 24 which extends coaxially and leftwardly outV of the end member 13. As indicated schematically in FIGURE 2, the leftward end of the opening 24 is connectible to a suitable source S of uid under pressure, for example, a compressed air line.

The valve 10 is particularly intended for use with elastic uids and, more particularly, with compressed air. However, its use with a wide variety of fluids is contemplated and the valve 10 may be used with inelastic uids given proper external controls. The source S is capable of alternatively supplying uid under pressure to the inlet opening 23 and. thereafter lowering the pressure at the inlet opening 23. Thus, the source S can be considered. a source of fluid pressure pulses. In the case of a compressed air source, the source may be arranged if desired to vent the opening 23 to the atmosphere at the end of a pressure pulse.

The rightward end wall of the rightward end member 14 is provided with Ia preferably coaxial outlet opening 26 therethrough for connecting the program-ming valve 10 to a suitable load indicated schematically at L. The load L may be of substantially'any desired type ener- 4' gizable by fluid under pressure such as, for example, a conventional pneumatic or hydraulic cylinder.

In the preferred embodiment of the invention shown, the programming valve 10 is connected to the load L by means of a coaxial conduit 31 extending rightwardly therefrom. The conduit 31 has a central passage 32. Ther Suitable seal means are provided between theconduit 31 and the wall of the outlet opening 26 to prevent leakage of fluid from the recess 12 therepast. Such seal is accomplished, in the particular embodiment shown, by provision of a plurality of axially spaced, lannular grooves 36 in the periphery of the conduit 31. A resilient sealV ring, preferably an O-ring 37 is alternatively disposable in one of the grooves 36 for snug insertion within the f opening 26 in order to prevent fl-uid'ow from the cham-V ber 12 therepast. It is contemplated, however, that a plurality of such O-rings 37' may be used to simultaneously equip a corresponding number of the grooves 36.

A plurality of regularly spaced indentations 39 are dis. posed along the axial length of the conduit 31 and preferarbly alternate with the grooves 36 such lthat each ofthe grooves 36 has a corresponding indentation 39 disposed to the right thereof. In the particular embodiment shown, the indentations 39 are ann-ular and of V-shaped cross section as shown in FIGURE 2 and are centered between the grooves 36. A set screw 41 is radially threaded Y through the periphery of the end member 14 into the outlet opening 2-6 for'engagement with the nearest one of the indentations 39, the set screw 41l preferably being provided with a pointed inner end 42 corresponding in shape to the cross section of the indentations 39. Thus,

the set screw y41 may be adjusted inwardly and seated within one of the indentations 39 to secure the conduit 31 axially with respect to the housing 11.

In FIGURE 2, the conduit 31 is shown in its rightwardmost position whereby the O-ring 37 is disposed in the leftwardmost one of the grooves 36, the set screw 41 is located to the right of the O-ring V37 and engages the leftwardmost one of the indentations 39 and the leftward radial face 43V of the conduit 31 is substantially coplanar with the closed end -of the recess 18.

The adjacent er1-ds of the end members 13 and 14 are preferably provided withcoaxial, annular and axially extending recesses 46 and 47, respectively. The recesses 46 and 47 preferably have identical inside and outside diametersV and are therefore directly axially opposed.

The annular recesses 46 and 47 are radially separatedv Y the ends of the `corresponding -annular reces1es and annulanilanges, whereby the radially outer wall of each of the annular recesses 46 and 47 is shorter than the radially inner wall thereof.

The extension structure 16 includes a cylindrical shell 56, the ends of which are snugly but slideably disposable in the annular recesses 46 an-d 47 of the end members 13 and 14. The ends of the shell 56 are preferably axially clear of the ends of the recesses 46 and 47. Suitable seal means are provided between the outer surfaces ofthe annular flanges 48 and y49 and the opposed inner wall of the shell 56 to prevent leakage therepast from the chamber 12. In the preferred embodiment of the invention shown, such seal means include annular grooves 57 and 58 in the periphery of the flanges 48 and 49 adjacent the inner vends thereof and seal rings, preferably O-rings, 61 and 62 disposed in the grooves. The'seal rings 61 and 62 resiliently bear against the inner surface of the shell 56. Thus, the shell 56 acts as a continuation of the wall of the housing 11 for joining the end members 13 and 14- in a rigid and leak-proof manner.

The extension structure 16 further includes abutment means, preferably comprising an axially arranged series of identical abutment members 63. In the particular embodiment shown, the abutment members 63 are annular and lie coaxially and snugly within the shell 56. The abutment members 63 each have la radially inwardly eX- tending annular flange 64 at the leftward end thereof, the inner surface of which is equal in diameter of the recess 17 in the leftward end member 13. The remaining inner surface 66 of each of the abutment members 63 to the right of the flange 64 is equal in diameter to the recess 18 in the rightward end member 14. The rightward face of the flange 64 preferably slopes, here at an angle of approximately 45, outwardly and rightwardly as indicated at 67 for purposes appearing hereinafter. The axial length of the surface `66 preferably exceeds that of the flange 64 including the sloped portion I67. The flan-ge 64 has a radial leftward wall 68 which provides a step-like abutment surface for purposes appearing hereinafter. The axial length of the members 63 and, hence, the axial spacing between .adjacent abutment surfaces 68 is preferably identical to the spacing of the indentations 39 on the conduit 31.

Elongated screws indicated at 69 in FIGURE 1 and broken lines in FIGURE 2, here four in number, extend axially through the end member 13 past the cylindrical shell 56 and preferably threadedly engage the member 14. Tightening of the screws 69 urges the ends of the franges 4S and 49 lon the members 13 land 14 tghtly against the abutment members y63 disposed therebetween to form, with the shell 56, a rigid funt.

An 4axially extended and substantially cylindrical piston 71 is axially reciprocable between the ends of the chamber 12. The walls of the recess 17 and the flanges 64 snugly support the piston 71. The piston 71 includes a head 72 at the rightward end thereof. An annular skirt 73 extends coaxially lleftwardly from the head 72 for defining a coaxial, leftwardly facing recess 74. The recess 74 receives the rod 21 loosely therewithin. The rightward end of the rod 21 lies near the rightward end of the recess 74 when the piston skirt 73 abuts the leftward end of the recess 17. Suitable seal means are preferably provided between the piston land the wall of the chamber 12 to prevent leak-age of pressure fluid between the inlet and outlet `openings therebetween. In the particular embodiment shown, the seal means includes an annular groove 77 -in the peripheral surface of the piston skirt 73 adjacent the leftward end thereof. A sealing element, preferably an iO-ring 78, is disposed in the groove 77 and bears resiliently tand continuously against the peripheral wall of the recess 17.

A valve 76 is disposed in the head of the piston 71. The valve 76 normally closes in response to .a pressure difference across the piston in either axial rdirection when the piston is intermediate the ends of its travel. The valve 76 is arranged to open and allow pressure fluid flow through the head of the piston and, hence, .between the inlet opening 23 and outlet opening 26 when the piston is Iat either end of its travel. In the particular embodiment shown, the valve 76 includes an fopening 81 coaxially extending through the head 72. The opening 81 is substantially smaller in diameter than the recess 74 in the skirt of the piston 71. The leftward and rightward ends 82 and -83 of the opening 81 are radially enlarged and provide substantially conical and outwardly opening valve seats 86 and 87, respectively.

The valve 76 further includes a movable member generally indicated at 89 which preferably comprises an elongated slug 91 of square cross section as seen in FIGURE 7 snugly but slideably disposed in the central portion 92 of the opening 81. The axial length of the slug 91 exceeds that of the central portion 92, preferably by a fraction of the diameter of the portion 92. The sides of the slug 91 are spaced from the periphery of the central por'- tion 92 to provide a plurality of axially extending chordal passages 93 therebetween. Resilient closure members 96 and 97 are atxed to the leftward and rightward ends, respectively, of the slug 91 by any convenient means, here comprising a pair of screws 98 and 99 coaxially affixed to the ends of the slug 91. The adjacent ends 101 and 102 of the closure members 96 and 97, respectively, are preferably conical to correspond in shape to the conical seats 86 and 87 lying adjacent thereto. Contact between the faces 86 and 101 as shown in FIGURE 2 or between the faces 87 and 102 closes the valve 76. When the faces 101 and 102 are both axially spaced from their respective seats S6 and 37, the valve is open and allows iiuid flow past the resilient closure members 96 and 97 and through the passages 93 from one end of the opening 81 to the other. The leftward and rightward ends, respectively, of the resilient closure members 96 and 97 radially clear the corresponding ends 82 and 33 of the opening 81 and are preferably tapered to maximize such clearance, in order to minimize the resistance to uid ilow therepast.

Rightward movement of the piston 71 into adjacency with the outlet conduit 31 causes the movable member 89 to strike the end 43 of the conduit 31 and be moved leftwardly with respect to the piston 71 to open the valve 76. 0n the other hand, upon movement of the piston into adjacency with the leftward end of the recessv17, the rightward end of the trip rod 21 strikes the head of the screw 98 to shift the movable member 89 rightwardly into its intermediate position for opening the valve '76.

A radially expandable stop mechanism 107 is carried by the piston 71 and is actuable for engaging successive ones of the abutment surfaces 68 on the abutment members 63 to prevent movement of the piston rightwardly therebeyond. The stop mechanism 107 and the abutment members 63 together comprise a counting structure as hereinafter described. In the preferred embodiment of FIGURES 2 and 3, the stop mechanism 107 is disposed in an annular groove 111 in the piston 71. The groove 111 is radially spaced from the leftward end S2 of the opening 81 and communicates therewith through a plurality of restrictive orifices 112 radially disposed in said piston. A resilient sealing ring 113, hereof generally U- shaped cross section is snugly disposed in the groove 111 for radial expansion and contraction therein. The sealing ring 113 prevents leakage of fluid under pressure outwardly therepast along the walls of the groove 111. A plurality lof generally keystone-shaped stop elements 116 are circumferentially arranged in the groove 111. The stop elements 116 are provided with communicating, rightwardly facing circumferential grooves 117 in which is disposed a resilient annular tension element, here a helical spring 118. The spring 118 normally urges the stop elements 116 and sealing ring 113 radially inwardly as indicated in FIGURE 4 so that the stop elements 116 do not extend beyond the periphery of the piston 71. Fluid in the groove 111 behind the sealing ring 113 at a pressure above a predetermined value will expand the ring, thereby overcoming the spring 118 and moving elements 116 outwardly beyond the periphery of the piston 71 and against the opposed one of the abutment members 63. The rightward face 119 of each of the stop elements 116 is preferably radial for engaging the opposed one of the abutment surfaces 68 on the abutment members 63 as indicated in FIGURE 2 to prevent rightward `movement of the piston therepast.

The periphery of each lof the stop elements 116 is preferably tapered to provide a sloped leftwardly facing surface 121. The sloped surface 121 allows the stop elements 116 to radially clear the flanges 64 on the abutment members 63 more quickly during rightward movement of the piston 71 and, moreover, acts with the sloped surface 67 on the abutment members to prevent interference between the stop elements 116 and the abutment members 63 which might hinder leftward movement of the piston.

OPERATTON Although the operation of the preferred embodiment of the invention has been indicated to some extent hereinabove, the same will now be summarized to insure a more complete understanding of the invention.

The inlet opening 24 is normally connected by any convenient vmeans here indicated schematically by the line 122 to a source S capable of providing pulses of uid, such as air, under pressure. The outlet conduit 31 is connected by any convenient means, here indicated schematically by a line 123, to a load L of any desired type, such as a pressure uid cylinder .or a further valve to be actuated by fluid pressure.

The cycle of operation of the programming valve 10 can conveniently be consideredl to start with the piston 71 abutting the leftward end of the recess 17. Presentation by the source S of a pulse of lluid under pressure to the inlet 23 of the valve 10 pressurizes the portion of the chamber 12 to the left of the piston 71 as Well as the recess 74 and leftward end 82 of the opening 81.

VSince the chamber 12 to the right of the piston is initially surization of leftward end of the chamber 12 substantial-V ly immediately shifts the movable member' 89 of the valve 76 to the right. This shift seats the resilient member 96 against the seat 86 and, hence, closes the valve 76. Closure of the valve 76 prevents the pressure iluid on the inlet end of the chamber 12 from reaching the outlet end thereof. The resulting pressure drop across the piston 71 moves same rightwardly away from the inlet opening 23, such movement occurring very soon after the beginning of the pressure pulse and substantially with the closure of the valve 76.

The pressurized fluid at the leftward end 82 `of the opening 81 is supplied relatively slowly through the restrictive orifices 112 to the inner portion of the groove 1-11 behind the expandable seal element 113. The restC-.

will be suflicient as to overcome the inward force ofV the spring 118 and hence to move the seal ring 113 and stop elements 116 radially outwardly with respect to the piston 71 well before the rightward face 119 reaches the abutment surface 68 on the second member 63. In fact, it is preferred that as the stop elements 116 move with the piston 71 rightwardly past the ange 64 on the first, i.e., leftwardmost, one of the abutment members 63, the stop elements 116 will be moved outwardly past the periphery of the piston 116 and against the surface 66 of said first abutment member 63. Thus, continued rightward movement of the piston 71 will bring the rightward face Y 119 of the stop elements 116 against the abutment face 68 of the ange 64 on the second or next-to-the-leftwardf most abutment member 63 thereby preventing further movement of the piston 71.

No further action will take place in the valve 16 until the pressure in the inlet opening 23 drops below that pressurel required to overcome the spring 118. When such pressure does drop, marking the end of the rst pressure pulse, the inner end of the groove 111 exhausts through the orifices 112 thus allowing the spring 118 to retract the stop elements 116 so that they radially clear the adjacent second flange 64. The restrictive orilices 112 are preferably suiciently large as to allow exhausting of the groove 111 in a relatively short time, usually a fraction of a second. After the spring 118 has retracted the stop elements 116 to within the periphery of the piston 71, the valve 10 has completed its counting of the tirst pulse and is ready to count a second-pressure pulse.

Further action of the valve is suspended until a second pressure pulse occurs inthe inlet `opening 23. Upon the 8 occurrence of such'a second pressure pulse the piston is substantially immediately moved rightwardly. The restrictive orices 112 delay extension of the stop elements 116 until after the piston 71 has moved the rightward faces 119 of the retracted stop elements 116 rightwardly past Vthe abutment face 68 of the second abutment member 63.

As in the first pulse, the restrictive orices 112 are arranged so that the stop members 116 extend past the periphery of the piston 71 before the abutment face 68 of the third abutment member 63 is approached thereby. Thus, the piston is stopped by abutment of the stoprelements 116 against the abutment face 68 of the third abutment member 63. Cessation of the second pulse allows retraction of the stop elements 116 by the spring 118 as hereinabove 1described thereby completing the counting of the second pulse by the valve 10. Thus, it will be seen that the piston 71 mov-es rightwardly one step corresponding in length to the axial length of the corresponding abutment member 63 in response to the rise of a pressure pulse at the inlet end of the valve 10.

In the same manner, the piston 71 steps rightward in response to the initiation of each succeeding pressure pulse occurring at the input thereof until during the last of a preselected number of pulses it is halted by the leftward end 43 of the conduit 31. As the piston 71 nears the end 43, the head of the screw 99 on the movable valve member S9 strikes the end 43. Continued rightward movement of the piston into abutment with the'end 43 shiftsVV the movable member 89 along the opening 81 to its intermediate position thereby separating the seated surfaces 101 and 86 and allowing pressure iluid flow from the leftward end of the chamber 12 Ythrough the open valve 76 into the passage 32 of the outlet conduit 31 for energizing the load L. Y

At the end of this last pressure pulse, the pressure at the inlet. end of the chamber 12 drops below that in the outletv end so that a reverse pressure drop is created across the piston 71. The relatively high pressure in the outlet end of the chamber 12 causes the movable valve member 89 to shift leftwardly into a closed condition. Thus, the resilient member 97 moves leftwardly toy seat the surface 192 thereof against the seat 87 in the piston head to prevent pressure iluid flow leftwardly through the piston. The

pressurized uid trapped to the right of the piston quicklyY moves same leftwardly the length of the chamber 12 to return to its original position. As in the counting operation above described, the drop in pressure on the inlet side e of the piston 71 at the end of the last pulse allows the spring 118 to retract the stop elements 116.'The stop elements 116-.will therefore normally be at leastbeginning 17, the trip rod 21 strikes the head of lthe screw 98 causing the movable valve member 89 to move rightwardly with respect to the piston to its intermediate, open position thereby exhausting the rightward end of the chamber 12 as well as the load L through the valve 76 to the low pressure inlet side of said piston. The cycle of the valve may now be repeated upon occurrence of another series Y of pressure pulses from the source S.

Thus, in summary, it will be seen that the closed valve 1t)` counts a predetermined number of pressure pulses, threel in the Vembodiment shown in FIGURE 2, applied to the inlet thereof and opens to admit the last of theseV pulses to the load. The valve 10 resets itself at the end of the last pulse forv counting a further group of pulses.

The maximum number of pulses, which can be counted before the opening of the valve 10, corresponds tothe number of abutment members 63. If desired, the valve can be adjusted to count a lesser number of pulses by loosening the setscrew 41 and moving the conduit 31 leftwardly into the chamber 12 as indicated in FIGURE 4. The O-ring 37 may be removed to a new one of the -grooves 36 to remain in sealing contact with the periphery of the outlet opening 26 to the left of the screw 41 or, if desired, a further O-ring may be provided for placement in such new groove, the existing O-ring 26 being allowed to remain where it is in the leftwardmost groove 36 for increased convenience. Leftward movement of the conduit 31 through a distance equal to the sum of the spacing of a number of the indentations 39 reduces, by the same number, the pulses that will be counted before the valve opens. When the desired new position of the conduit 31 is reached, the setscrew 41 is tightened to engage a new one of the indentations 39 thereby fixing the conduit 31 in a new position on the housing 11.

The valve 10 is readily adapted to change the maximum number of pulses to be counted, prior to opening of the valve, to a new value. This is accomplished by loosening of the screws 69 to allow separation of the end members 13 and 14 and release thereby of the shell 56 thereby allowing removal or addition of members 63. This operation is readily carried out. For example, with the piston 71 adjacent its leftwardmost position, removal of the screws 69 from the end member 14 allows said end member to be moved rightwardly away Ifrom the remainder of the valve 1G. Thereafter, the shell 56 may be removed from the end member 13 and be replaced by a new one of length corresponding to the desired new quantity of abutment members 63. At the same time, the number of abutment members 63 may be reduced by removing some from the existing set or may be increased by adding further abutment members to the existing set. With the new shell 56 inserted in the recesses 46 and 47 in the end members 13 and 14 and with the new quantity of abutment members snugly disposed within the shell 56 and between the fianges 48 and 49 on said end members, the screws 69 are once again engaged with the end member 14 and tightened. Larger numbers of new abutment members 63 may be added to programming valves 10 having longer skirted pistons and deeper recesses 17 while still avoiding rightward movement of the O-ring 78 pa-st the leftwardmost liange 64 of the abutment members 63 and the resultant escape of fluid therepast. Alternatively, a larger number of abutment members 63 may be used if the length of the abutment members is decreased by a corresponding amount, the spacing of the outlet conduit indentations 39 and, if required, the axial dimension of the stop elements 116 undergoing a corresponding change.

Referring to FIGURE 12, there is disclosed a circuit 157 comprising a pair of programming valves 10 connected in tandem between a source S and a load L. More specifically, the source S connects through the line 122 to the inlet 24 of the first or upper valve 10, the outlet 32 of the upper valve 10 connects through a conduit 158 to the inlet 24 of the lower or second valve 10 and the outlet 32 of the lower valve 1i) connects through the line 123 to the load L. After the first valve 10 has counted the required number of pulses it opens to transmit a first output pulse to the inlet of the second valve 10. A second pulse is presented to the second valve 10 after the first valve has gone through a second counting sequence. This action continues until the second valve has been fed sufficient pulses to open same. As a result, the load L is energized upon occurrence of the last of a series of pressure pulses from the source S, the number of such pulses in such series being equal to the arithmetic product of the number of pulses required at the inlet of the iinst valve to open same and the number of pulses required at the inlet of the second valve to open same. As a result, a relatively large number of pulses may be counted by using two or more valves in series, said valves being capable i0 of counting only a relatively small number of pulses individually.

MODIFICATIONS FIGURE 5 discloses a modified embodiment of the invention including a modified stop mechanism 131. Portions of the device of FIGURE 5 corresponding to parts of the apparatus of FIGURE 2 will be designated by the same reference numerals thereas with the suix A added thereto. The end 82A of the Valve opening in the piston is preferably longer than the end S2 of FIG- URE 2 and the stop mechanism 131 is preferably spaced leftwardly along the opening 82A from the valve 76A. The stop mechanism 131 includes a plurality, preferably a diametrally opposed pair, of preferably circular recesses 132 which extend radially through the periphery of the piston 71A. The inner end of each of the recesses 132 communicates through a radial restrictive orifice 112A with the leftward portion of the opening end 82A and thereby with the recess 74A. A radially reciprocable piston 133 is snugly but slideably disposed in each of the recesses 132. An annular sealing member, preferably an O-ring 134, is seated in an annular -groove in the piston 133 intermediate the ends thereof for preventing leakage of uid radially past the piston 133. A retracting element, here comprising a helical tension spring 136, extends across the opening end 82A loosely through the orifices 112 and is connected at its ends to the pistons 133 for maintaining same within the periphery of the piston 71A in the absence of a predetermined fiuid pressure in the recess 74A. In the present embodiment, the spring 136 has hooked ends 137 which extend into recesses 133 in the inner ends of the pistons 133 for gripping transverse pins 139 therein.

The outer ends of the pistons 133 are preferably relieved on the leftward side thereof to provide a sloped portion 121A for the same purposes as the sloped tapered portion 121 described hereinabove. If desired, transverse holes 140 may be provided in the outer end of the piston 133 to facilitate removal of the pistons 133 yfrom the recesses 132 for servicing. The rightward side of the piston at its outer end indicated at 119A acts as a stop surface abutable with an abutment surface fixed with respect to the valve housing as hereinabove described with respect to the embodiment of FIGURE 2. When circular pistons 133 are used, any convenient means may be used to prevent rotation thereof in the recesses 132. In the present embodiment, a radial pin 141 is fixed in the bottom of the recess 132 outside the orifice 112A and is slideably received in an opening 142 in the inner end of the piston 133. The head 143 of the screw 98A is preferably extended leftwardly past the spring 136 and slotted as indicated at 144 to allow passage of the spring 136 therethrough and still allow actuation of screw 98A by the trip rod not shown corresponding to the trip rod 21 of FIGURE 2.

Thus, pressurization of the recess 74A results eventually in pressurization of the inner end of the pistons 133 through the restrictive orifices 112A thereby causing such pistons to overcome the spring 136 and move outwardly into abutting relation-ship with the abutment members 63A as described hereinabove with respect to the embodiment of FIGURE 2.

FIGURE 6 discloses a further modification of the stop mechanism. The stop mechanism 151 differs from the stop mechanism 107 of FIGURE 2 in that the separate stop elements 116, spring 118 and resilient sealing ring 113 lare replaced by a single radially expandable elastomeric ring 152. The ring 152 has an inner portion 153 which preferably corresponds to the sealing ring 113 of FIG- URE 2 in shape and function. The ring 152 has an outer portion 154 integral with the inner portion 153 which is substantially rectangular in cross section. The -leftward outer edge of the ring 152 is rounded at 156 substantially for the same reasons that the -portion 121 described hereinabove with respect to FIGURE 2 is tapered.

FIGURES 8, 9 and 10 disclose a -.modified programming valve 160. The modified valve 160 is, in its broad organization, substantially similar to the valve 10 above described and, thus, parts of the modified valve 160 corresponding to parts of the valve 10 will be referred to by the same reference numerals thereas with the suffix B added thereto. However, the valve 160 differs materially in detail from the valve 10 as hereinafter described.

The valve 160 includes a housing 11B comprising end members 13B and 14B separated by an extension structure 16B. The end members 13B and 14B are provided with coaxially opposed recesses 17B and 18B, respectively, of circular cross section which define an elongated chamber 12B. The recess 17B is of stepped cylindrical shape and includes a relatively shallow rightward portion 161 of diameter equal to that of the recess 18B and an elongated leftward portion 162 of reduced diameter which extends to a point near the leftward end of the end member 13B.

A rigid hollow conduit 166 extends coaxially from the A leftward end of the recess portion 162 to a point adjacent the rightward end of the end member 13B. In the particular embodiment shown, the leftward end of the conduit 166 .is press fitted within an opening 167 located coaxially in the leftward end of the recess 17B. The conduit 166 has a central opening 168 extending axially Y therethrough. The conduit 166 serves substantially the same purpose as the trip rod 21 of the valve 10. hereinabove described as well as an additional purpose hereinafter described.

The end member 13B is provided with a radial, threaded inlet opening 169 to the left of the recess 17B which is connectible, as indicated schematically in FIGURE 9, to a source S of fluid under pressure of the type described above with respect to the valve 10. A blind extension 171 of the inlet opening 169 extends coaxially therefrom through the central opening 168 of the conduit 166 and somewhat thereb'eyond for connecting the source S to said central opening.

An axial opening 172 connects the leftward end of the recess portion 162 adjacent the :periphery thereof with the lower end ofthe blind opening 171. An inlet valve 173 is adjustable for controlling the rate of pressure flow from the inlet opening 169 through the openings 171 and 172 into the leftward end of the recess 17B. In the. particular embodiment shown, the inlet valve 17?` comprises a screw 174 which threads through the leftward end of the end member 13B coaxially into the axial opening 172 and pastV the lower end of the blind opening 171 to prevent communication between the openings 171 and 172. A lock nut 176 is provided to lockthe screw 174 yin any desired position whereby the flow from the source S into the leftward end of the recess 17B can be held at a desired value less than or equal to the flow through the inlet opening 169 into the central opening 168 of conduit 166.

A further axial opening 177 is circumferentially spaced from the opening 172 and extends from the leftward end of the recess 17B adjacent the periphery thereof Ileftwardly into communication with the periphery of the inlet opening 169. A check valve 178 of any convenient type is disposed for blocking communication between inlet opening 169 andthe axial opening 177 until the pressure in the leftward end of the recess 17B exceeds that in inlet opening 169'by predetermined amount. In the particular embodiment shown, the cheek valve 178 comprises a screw 179 threaded axially through the leftward end wall of fthe end member 13B coaxially into the opening 177. A leftwardly opening conical valve seat 183 is dened by the walls of the opening 177 between the recess 17B and the inlet 169. The opening 177 is enlarged.

to the left of the valve seat 183. A valve head 181 is Vaxially slideably supported at its leftward end in an opening 180 in fthe rightward end of the screw 179. A spring 182 disposed in the openingg180 urges the tapered rightward end of the valve head 181 against the seat 183 t0 close the check valve 17 8.

An outlet opening 186 extends radially through the wall of the rightward end member 14B and is preferably threaded for connection to a load L which may be of the kind discussed with respect to the valve 10. The recess 18B is provided with a rightward, generally cylindrica'l extension 187 of reduced diameter. The inner end of the outlet opening 186 extends through the periphery of the extension 187 adjacent the rightward end thereof. A restricted, radial vent 188 is provided through the wall of the end member 14B at the rightward end of the Vre-l cess 18B to slowly exhaust any build-up of fluid pressure in the rightward end of the chamber 12B. j

The extension structure 16B comprises an axially arranged series of identical abutment members 63B (FIG- URES 9 and 11) which are substantially similar to the abutment members 63B of the valve/10 except as immediately hereinafterdescribed. Each of the abutment rnem-l bers 63B is provided at the periphery thereof with a rightwardly extending annular flange 191. The leftward peripheral corner of each abutment member 63B is reduced to form a leftward and forwardly facing annular groove 192. The flanges 191 and grooves 192 have corresponding, preferably rectangular cross sections-Thus, the groove 192 of one abutment member snugly receives the annular flange 191 of an abutment member 63B to the left thereof in telescoping fashion thereover to rigidly main-- tain the annular abutment members 63' concentric. The opposed faces of the end members 13B and 14B are provided with a corresponding flange 193 andigroove'194, respectively, for snugly'engaging the adjacent groove 192` and flange 191, respectively, of the adjacent abutment small angle to the. radial which in the present embodiv ment is approximatey 10. The inner surfaces of the' inwardly extending annular flanges 64B are preferably of the same radius as the 'rightward portion 161 ofthe recess 17B.

The end members 13B and 14B and the extension structure 16B are held yaxially together by Vbolts 69B (FIGURES 8, 9 and 10) which'pass through suitable openings 1196 in the end members 13B and l14B adjacent the cor-ners thereof and are provided `with suitable nuts 197. i Y' The piston- 71B differs substantially from the piston 71 0f the valve 10. More specifically, the piston 71B includes an elongated, substantially cylindrical skirt 198: The skirt 198 is relatively small in diameter as compared with its length and fits snugly'but slideably within the leftward portion 162 of the recess 17B. When the piston is in its leftwardmost position shown, the leftward end thereof lies near the leftward end of therecess 17B. An O-ring 78B is providedat the leftward end of the skirt 198 to prevent leakage of fluid in the leftward end of the recess 17B therepast. The piston 71B has a central opening 201 which extends axially therethrough. The conduit 166- is snugly but slideably received within the central opening 201 and is preferably provided at the rightward end thereof with a suitable O-ring 262 for preventing leakage therepast.

The piston V71B includes an enlarged head generallyy indicated at' 203 (FIGURES 9'and 11). The head 203` includes a radial flange 204 located at the rightward end of the skirt 193. The radial flange 204 is snugly but slideably receivable into the enlarged leftward portion 161 for reasons appearing hereinafter. The head 203 further includes a substantially cylindrical portion 206 extending rightwardly from the flange 204. The rightward portion 206 lits snugly but slideably within the recess extension 187 in the end member 14B when the piston 71B is in its rightwardmost position. Suitable seal means, preferably an O-ring 207 is provided near the end of the rightward portion 206 and coacts with the peripheral wall of the recess extension 187 to prevent leakage between the outlet opening 186 and the recess 18B when the piston is in its rightwardmost portion.

The rightward portion 206 of the head 203 is equipped with a valve 76B, which in the present embodiment is substantially identical to the valve 76 of FIGURE 2. The valve 76B is located within the restricted portion 92B of the central opening 201 of the piston. The leftward and rightward ends 98B and 99B of the slug 91B of the valve 76B are arranged in the programming valve 160 to close the valve 76B upon being firmly urged against the rightward end of the conduit 166 and against the rightward end wall of the recess extension 187, respectively, when the piston is at its leftward or rightward limiting positions, respectively. In the particular embodiment shown, the rightward end of the conduit 166 is radially slotted at 211 to connect the rightward end of the conduit opening 168 and the reduced diameter portion 92B of the central opening 201 when the slug end 98B engages the rightward end of the conduit 166.

The piston head 203 further includes an annular collar 212 (FIGURES 9 and 11) spaced rightwardly from the radial ange 204 on the rightward portion 206. A snap ring 213 is disposed in a suitable groove in the portion 206 to the left of the O-ring 207 to prevent rightward movement of the collar 212 on the portion 206. Suitable seal means, preferably an O-ring 214 is provided in a suitable groove in the rightward portion 206 just to the left of the snap ring 213 for snugly engaging the bore of the collar 212 to prevent passage of pressure fluid rightwardly therepast. Thus, the spaced annular ange 204 and collar 212 define therebetween an anular groove 111B corresponding to the groove 111 of FIGURE 2. The groove 111B is preferably somewhat larger in axial extent than the groove 111.

The groove 111B houses a suitable stop mechanism 107B and communicates through restrictive orifices 112B with the central opening 201 just to the left of the restricted portion 92B thereof. The stop mechanism 107B includes a sealing ring 113B and stop elements 116B. The stop elements 116B differ in cross section from the elements 116 of FIGURE 2 and are of outwardly opening substantially U-shaped cross section. The stop elements 116B each have an upstanding, tapered left leg 217. The rightward face of the leg 217 is sloped away from the radial plane and'parallels the abutment surface 68B on the abutment members 63B. The leftward corner of the leg 217B is tapered as indicated at 121B. The rightward leg 21S of the stop element 116B is shorter than the leg 217. When the stop element 116B is retracted as shown in FIGURE 11, the rightward leg 218 is spaced radially inwardly from an overhanging axial ange 219 on the leftward face of the collar 212, the ange 219 acting with the leg 218 to maintain the stop element 116B within the groove 111B. A resilient ring 118B which, for example, may be an elastomeric band or, as in the embodiment of FIGURE 2, a spiral spring surrounds the bight 220 of the stop elements 116B and urges same inwardly to normally maintain the leg 217 axially clear of the abutment surfaces 68B on the abutment members 63B.

The operation of the programming valve 160 is broadly similar to that described hereinabove with respect to the programming valve 10. However, there are a number of detailed diiferences as pointed out hereinbelow.

A rise in the pressure of the source S results in passage of pressure fluid through the inlet 169 and opening 171, past the rightward end of the screw 174 of the valve 173, through the opening 172 and into the left- Ward portion 162 of the recess 17B. Such flow is readily regulated by threading the screw 174 back and forth across the end of lower end of the opening 171. As the flow of pressure fluid into the leftward end of the chamber 12A continues, the piston is moved gradually towards the right from its position shown, the speed of' such movement being controlled by the setting of the valve 173.

At the same time, pressure uid from the inlet 169 passes from the opening 171 into the central opening 168 of the conduit 166. Fluid under pressure in the central opening moves the leftward end 98B of the slug 91B rightwardly to close the valve 76B. Pressure fluid from the central opening 168 also flows through the restrictive orifices 112B and into the groove 111B within the seal 113B, the orilices 112B metering uid flow so that pressure in the groove rises gradually. Eventually iluid pressure in said groove rises to a value sufficiently large as to overcome the resilient element 118B and urge the stop elements 116B outwardly into interferring relationship with the abutment members 63B.

By suitable adjustment of the valve 173, the speed at lwhich the piston 107B moves rightwardly can be regulated for a wide range of input pressures. Normally, therefore, the piston will axially move the legs 217 of the stop elements 116B past the adjacent one of the abutment surfaces 68B before the resilient element 118B is overcome and the stop eements 116B are moved outwardly into interferriug relationship with the abutment members 63B.

If desired, the valve 176 can be opened to speed up the movement of the piston. In this manner, the piston, with the stop elements 116B may be moved past two or more of the abutment members 63B before expansion of the seal ring 113B overcomes the resilient element 118B. Thus, without dismantling of the valve and by a very simple adjustment of the inlet valve 173, the number of pulses counted by the valve 160 can be changed.

Sloping of the abutment surfaces 68B and of corresponding faces of the legs 217 allows the stop elements 116B to be retracted more easily since friction therebetween is largely eliminated. As a result, a smaller resilient member 118B can be utilized to retract the stop elements 116B. This, together with the greater axial length of the groove 111B reduces the opening pressure required within the groove for extending the stop elements.

No member corresponding to the conduit 31 of FIG- URE 2 occurs in the valve 160 and the valve 160 is correspondingly simplified thereby and by the elimination of the extra seal 37 required by the conduit 31.

The fluid entrapped before the rightwardly advancing -piston head 203 is vented through the opening 188 thus preventing any premature build up of fluid pressure in the load. After counting the last of a number of pulses, normally equal to the number of the abutment members 63B provided, the head 203 of the piston 107B enters the recess 18B and strikes the rightward end thereof. The rightward end 99B of the slug 91B is thereby forced leftwardly in the head 203 by the rightward end of the recess extension 187 to open the valve 76B. This allows pressure fluid flow from the conduit 166 past the slug 91B, into the recess extension 187 and out the outlet 186 to the load L.

At the end of the last pressure luid pulse, the pressure at the inlet 169 drops below that in outlet 186 and below that in the leftward end of the recess 17B. The resulting pressure drop across the check valve '178 opens same and the leftward end of the recess 17B is thus vented through the check valve 178 and to some extent through the valve 176 to the inlet opening 169. Moreover, the pressure within the'central openings 168 and 201 also drops to the low pressure of the inlet 169. A pressure drop thus occurs across the valve 76B from the right side to the left side thereof which urges the slug 91B thereof leftwardly to close same. With the valve 76B closed, the resulting relatively high pressure to the right of the piston 71B urges same leftwardly to its position shown inFIGURE 9. The opening 188 is sufficiently restrictive that the pressure to the right of the piston 107B is not appreciably affected thereby in the relatively small Vshort timerequired to move the piston leftwardly. As the piston assumes its Vleftwardmost position shown, the leftward end 98B of the valve slug 91B strikes the end of the conduit 166-andis moved rightwardly in the head 203. As a result, the valve 76B is opened toallow the pressure to the load L to exhaust therethrough and through the conduitV 16S to the inlet opening '169.

Although particular preferred embodiments of the inventiony have been disclosed hereinabove for illustrating purposes, it will be understood that variations or modificat tions thereof which lie within'the scope of the appended claims are fully contemplated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a programming valve, the combination comprising: v

means defining a chamber;

piston means movable along said chamber in theidirection of decreasing pressure in response to a pressure drop thereacross;

counting means responsive to successive pressurizations of said chamber on one side of said piston for allowing su-ch movement of said piston through successive steps of limited length;

means responsive to the position of said piston in said chamber for controlling fluid iiow with respect to said piston.

2. In a programming valve for counting pressure fiuid pulses, the combination comprising:

a housing having inlet and outlet openings and a chamber connecting same;

a piston reciprocable in said chamber between said inlet and outlet openings in response to a net fiuid pressure thereon;

a further opening for connecting said chamber on one side of saidpiston to said chamber on the other side of said piston and a valve member shiftable infresponse to a pressure drop across said piston for controlling fluid flow through said further opening;

means fixed with respect to said housing for shifting said valve member as said piston approaches the inlet and outlet openings to control fluid flow between said inlet and outlet openings; y

cooperating means associated with said housing and piston actuable in response to a predetermined uid pressure at said inlet opening for limiting movement of saidpiston away from said inlet opening.

3. In a programming valve connectible between a source of gas andV a load, the combination comprising:

a housing having inlet and outlet openings and a chamber connecting same;

a piston axially reciprocable between the ends of said chamber in response to gas pressure thereon;

a plurality of axially spaced steps in the periphery of saidchamber;

means radially extendable from said piston in response to an increase in gas pressure in said inlet opening for engaging'the next one of said steps so that further movement of said piston toward said outlet is prevented;

means for delaying radial extension of said extendable means until the piston has moved same past one of said steps;

an opening extending axially through said piston and a valve member disposed in said opening for reciprocation therealong, said Valve member closing said opening in response to a pressureV drop in either direc- 16' tion across said piston when said piston is intermediate the ends-of said chamber;

actuating means at the ends of said chamberengageable with said valve member for opening same as said piston reaches the ends of its travel.

4. The device defined in claim 3, in which said housing comprises a pair of end members separated by a cyiindrical shell and including a plurality of abutment rings disposed snugly within said shell and between the ends of said end members, each of said abutment rings having an inwardly extending annular flange,- the inside diameter of said fianges corresponding to the diameter of one end of said chamber and the inside diameter of said rings adjacent said fianges corresponding to the inside diameter of the other end of saidY chamber, each of said flangesY having a substantially radial abutment surface on the inlet side thereof and a tapered surface on the outlet' side thereof, said abutment surface being engageable by said extendable means to prevent movementV of said piston toward said outlet opening.

5. The device defined in claim 3, including an axially extended outlet conduit disposed 'in said outlet opening for feeding the load, one of said actuating means-com-V duit toward and away from said piston.

6. The device defined in claim 3, in which said valve member comprises an axially extended slug having `at least one substantially axially extending passage defined between the periphery thereof and the Wall of said opening and a resilient closure member at each end thereof, said slug being snugly but reciprocably received in said opening in said piston, said opening having radially enlarged ends including valve seats whereby closure of said opening is effected by movement of one of said resilient closure members against the adjacent one of said seats in response to fluid pressure thereon.

7. The device defined in claim 3, in which the radially extendable means comprises a plurality of circumferentially arranged stop elements disposed inan annular groove in said piston, an expandable, annular seal member engageable with the inner ends of said segments and a resilient annular element engaging said stop elements for urging same radially inwardly to a position within the periphery of said piston and a pluralityY of restrictive orifices allowing communication between the inside of said groove and said inlet opening whereby pressurization of said inlet opening-'results in movement of said Ystop elements outwardly beyond the periphery of said piston for engaging said steps after a time delay required for passage of pressure uid through said restrictive orifices.

8. The device defined in claim 3, in which said piston includes a plurality of diametrally opposed, radial recesses in the periphery thereof; and

in which said radially extendable means comprises a plurality of pistons disposed for radial reciprocation in said recesses from a position Within the periphery of the piston to an extended position in axial opposition to said step means;

a radial restrictive orifice at the inner end of each of said recesses; and a resilient member extending through said restrictive orifices and connected to the inner ends of said pistons for urging same inwardly, said restrictive orifices being in communication with said source and allowing pressurization of the inner ends of said pistons thereby to effect radially outward movement of said pistons.

9. The device defined in claim 3, in which a circumferential groove is provided in said piston and a plurality Y means for allowing axial adjustmentof said outlet con.

munication between the inner end of said groove and said source; and

in which said radially extendable means comprises a resilient ring normally lying within said groove and capable of radial expansion into axial opposition with said steps in response to iluid pressure in the inner portion of said groove.

1). The device dened in claim 3, in which said piston includes an axially opening recess for providing access to said valve member and n which said actuating means includes a member extending from one end of said chamber into said recess, said member being engageable with said valve member upon movement of said piston toward said one end of said chamber for opening said valve member.

11. The device deiined in claim 2, including a uid passage connecting said inlet opening with said chamber on the inlet side of said piston, a second passage independent ofthe first passage for connecting said inlet opening to said further opening and inlet valve means adjustable for regulating the flow of pressure uid through at least one of said passages.

12. The device defined in claim 3, in which said actuating means including an axially extending conduit iixed to said housing adjacent said inlet opening and communicating therewith, said conduit being snugly but slideably received within said axial opening through said piston for supplying pressure fluid to one side of said valve member, said conduit being arranged to open said valve member when said piston approaches the inlet end of its travel.

13. The device deiined in claim 2, in which a check valve is connected between the inlet end of said chamber and said inlet opening, said check valve opening in response to a pressure drop from said chamber to said inlet opening.

14. The device defined in claim 3, in which said housing includes a pair of axially spaced end members separated by a plurality of abutment rings and including means snugly holding said end members and abutment rings axially together, the facing surfaces of said abutment rings and end members having axially extending overlapping means for maintaining same concentrically located with respect to each other, each of said abutment rings having an inwardly extending tapered ilange, one side of which is engageable by said extendable means to prevent the movement of said piston toward said outlet opening.

15. The device defined in claim 2, in which said chamber has a restricted vent adjacent said outlet opening for preventing a pressure build up in the outlet end of said chamber due to movement of said piston toward said outlet opening.

16. The device defined in claim 7 wherein each of said stop elements has a radially outwardly opening, substantially U-shaped cross section defining a pair of legs and a bight connecting same, in which one of said legs is capable of extension beyond said groove for engaging said steps, the other of said legs is shorter than said one leg and said groove has an axially extending ange adjacent the outer end thereof overlying said other leg, interference between said other leg and said ilange limiting outward movement of said stop element, said resilient annular element bearing resiliently inwardly on the bight portion of said stop element to urge same toward the inner end of said groove.

No references cited.

M. CARY NELSON, Primary Examiner.

R. J. MILLER, Assistant Examiner. 

1. IN A PROGRAMMING VALVE, THE COMBINATION COMPRISING: MEANS DEFINING A CHAMBER; PISTON MEANS MOVABLE ALONG SAID CHAMBER IN THE DIRECTION OF DECREASING PRESSURE IN RESPONSE TO A PRESSURE DROP THEREACROSS; COUNTING MEANS RESPONSIVE TO SUCCESSIVE PRESSURIZATIONS OF SAID CHAMBER ON ONE SIDE OF SAID PISTON FOR ALLOWING SUCH MOVEMENT OF SAID PISTON THROUGH SUCCESSIVE STEPS OF LIMITED LENGTH; 